Low latency input object detection under low ground mass condition

ABSTRACT

A processing system configured to detect an input object proximate the processing system. The processing system includes sensor circuitry configured to make a determination, when the processing system is in a low ground mass (LGM) state, that a large object is proximate to sensor electrodes of the processing system. The sensor circuitry is further configured, in response to a determination that a large object is proximate the sensor electrodes while the processing system is in the LGM state, to drive a first group of sensor electrodes with one of an inverted signal or a non-inverted signal and drive a second group of sensor electrodes with a static DC voltage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and thereby claims benefit under35 U.S.C. § 120 to, U.S. patent application Ser. No. 17/522,679 filed onNov. 9, 2021, which is incorporated herein by reference in its entirety.

BACKGROUND

Input devices including proximity sensor devices (e.g., touchpads ortouch sensor devices) are widely used in a variety of electronicsystems. A proximity sensor device typically includes a sensing region,often demarked by a surface, in which the proximity sensor devicedetermines the presence, location, or motion of one or more inputobjects. Proximity sensor devices may be used to provide interfaces forthe electronic system. For example, proximity sensor devices are oftenused as input devices for larger computing systems (such as opaquetouchpads integrated in, or peripheral to, notebook or desktopcomputers). Proximity sensor devices are often combined with displaydevices to operate as input-display devices (such as touch screensintegrated in cellular phones).

Some proximity sensor devices are configured to detect capacitive pensignals. The capacitive pen transmits the capacitive pen signalsresponsive to the capacitive pen detecting an uplink signal from theproximity sensor device. The proximity sensor device transmits theuplink signal that a sensor in the tip of a capacitive pen detects. Thedetection circuit in the capacitive pen uses the body of the capacitivepen as a reference. Namely, the detection circuit detects the uplinksignal based on the difference between signals from the capacitive pentip and the capacitive pen body. However, when a proximity sensor devicetransmits the uplink signal and the user's palm is in the sensingregion, both the palm of a user's hand and the capacitive pen tipreceive the same signal. As a result, the user's palm couples the sameuplink signal to the capacitive pen body, so that the capacitive penbody and the capacitive pen tip both receive same signal. In this case,the difference will be zero, so the detection circuit does not detectthe uplink signal. As a result, the capacitive pen does not transmit thecapacitive pen signals, and the proximity sensor device does not detectthe capacitive pen.

SUMMARY

In general, it is an object of the present disclosure to describe aprocessing system configured to detect an input object proximate theprocessing system. In an exemplary embodiment, the processing systemincludes sensor circuitry configured to make a determination, when theprocessing system is in a low ground mass (LGM) state, that a largeobject is proximate to sensor electrodes of the processing system. Thesensor circuitry is further configured, in response to a determinationthat a large object is proximate the sensor electrodes while theprocessing system is in the LGM state, to drive a first group of thesensor electrodes with one of an inverted signal or a non-invertedsignal and drive a second group of the sensor electrodes with a staticDC voltage.

It is another object of the present disclosure to describe a method ofdetecting an input object proximate a processing system. The methodincludes: i) making a determination that the processing system is in alow ground mass (LGM) state; and ii) making a determination that a largeobject is proximate sensor electrodes of the processing system. Inresponse to a determination that the processing system is in an LGMstate and that a large object is proximate the sensor electrodes of theprocessing system, the method further includes driving a first group ofthe sensor electrodes with one of an inverted signal or a non-invertedsignal and driving a second group of the sensor electrodes with a staticDC voltage.

It is another object of the present disclosure to describe an inputdevice configured to detect an input object proximate the input device.The input device includes sensor electrodes configured to transmituplink signals to the input object and a processing system coupled tothe sensor electrodes. The processing system is configured to make adetermination that the input device is in a low ground mass (LGM) stateand to make a determination that a large object is proximate the sensorelectrodes. In response to a determination that the input device is inan LGM state and that a large object is proximate the sensor electrodes,the processing system drives a first group of the sensor electrodes withone of an inverted signal or a non-inverted signal and drives a secondgroup of the sensor electrodes with a static DC voltage.

Other aspects of the disclosure will be apparent from the followingdescription and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

The present embodiments are illustrated by way of example and are notintended to be limited by the figures of the accompanying drawings.

FIG. 1 shows a block diagram of an input device in accordance with oneor more embodiments.

FIG. 2A shows a portion of an example sensor electrode pattern may beutilized in a sensor to generate all or part of the sensing region ofthe input device according to various embodiments.

FIG. 2B illustrates an example matrix array of sensor electrodes,according to various embodiments.

FIG. 3 illustrates capacitive pen detection according to one or moreembodiments.

FIG. 4 illustrates capacitive pen detection according to one or moreembodiments.

FIG. 5 illustrates normalized uplink signal levels during pen detectionin FIG. 3 and FIG. 4 according to one or more embodiments.

FIG. 6 is a flow diagram illustrating uplink driving according to one ormore embodiments.

DETAILED DESCRIPTION

Specific embodiments of the disclosure will now be described in detailwith reference to the accompanying figures. Like elements in the variousfigures are denoted by like reference numerals for consistency.

In the following detailed description of embodiments of the disclosure,numerous specific details are set forth in order to provide a morethorough understanding of the disclosure. However, it will be apparentto one of ordinary skill in the art that the disclosure may be practicedwithout these specific details. In other instances, well-known featureshave not been described in detail to avoid unnecessarily complicatingthe description.

Throughout the application, ordinal numbers (e.g., first, second, third,etc.) may be used as an adjective for an element (i.e., any noun in theapplication). The use of ordinal numbers is not to imply or create anyparticular ordering of the elements nor to limit any element to beingonly a single element unless expressly disclosed, such as by the use ofthe terms “before”, “after”, “single”, and other such terminology.Rather, the use of ordinal numbers is to distinguish between theelements. By way of an example, a first element is distinct from asecond element, and the first element may encompass more than oneelement and succeed (or precede) the second element in an ordering ofelements.

The present disclosure describes an input device that provides quickerdetection of a capacitive pen (i.e., stylus or active pen) under lowground mass (LGM) conditions. When an input device (e.g., a mobilephone) is plugged in and charging or is held in the user's hand, a goodground condition exists. However, if the input device is resting on atable or other object, the input device may be in an LGM state (i.e.,does not have a good ground condition). In the LGM state, the detectioncircuit in the capacitive pen may fail to detect the uplink signaltransmitted by the proximity sensor device because both the palm of theuser's hand in contact with the surface of the proximity sensor deviceand the capacitive pen tip receive the same signal. In this case, thedifference in the signals is substantially zero, so that the uplinksignal is not received by the capacitive pen. As a result of thecapacitive pen failing to detect the uplink signal, the capacitive penfails to transmit capacitive pen signals and, correspondingly, the inputdevice fails in detecting the capacitive pen.

Under LGM conditions, there are a few cases that may occur when thecapacitive pen and palm approach the surface of the proximity sensordevice. In Case 1, the hand of the user reaches the surface of theproximity sensor device before the capacitive pen. In Case 2, the tip ofthe input object reaches the surface before the hand. In Case 3, the tipof the input object and the hand reach the surface of the proximitysensor device at the same time. A traditional uplink drive in which thewhole panel is driven at a same phase works for Case 2, but not for Case1 and Case 3. The present disclosure describes an input device thatreduces the latency associated with Case 1 in accordance with one ormore embodiments.

Turning now to the figures, FIG. 1 shows a block diagram of an exemplaryinput device 100, in accordance with embodiments of the disclosure. Theinput device 100 may be configured to provide input to an electronicsystem 101. The input device 100 comprise processing system 110, displayscreen 155, and one or more control buttons 130. Processing system 110includes determination circuitry 150 and sensor circuitry 160 and isoperatively coupled to display screen 155 and control buttons 130.

As used in this document, the term “electronic system 101” (or“electronic device 101”) broadly refers to any system capable ofelectronically processing information. Examples of electronic systemsmay include personal computers of all sizes and shapes (e.g., desktopcomputers, laptop computers, netbook computers, tablets, web browsers,e-book readers, and personal digital assistants (PDAs)), composite inputdevices (e.g., physical keyboards, joysticks, and key switches), datainput devices (e.g., remote controls and mice), data output devices(e.g., display screens and printers), remote terminals, kiosks, videogame machines (e.g., video game consoles, portable gaming devices, andthe like), communication devices (e.g., cellular phones, such as smartphones), and media devices (e.g., recorders, editors, and players suchas televisions, set-top boxes, music players, digital photo frames, anddigital cameras). Additionally, the electronic system could be a host ora slave to the input device.

The input device 100 may be implemented as a physical part of theelectronic system 101. In the alternative, the input device 100 may bephysically separate from the electronic system 101. The input device 100may be coupled to (and communicate with) components of the electronicsystem 101 using various wired or wireless interconnections andcommunication technologies, such as buses and networks. Exampletechnologies may include Inter-Integrated Circuit (I2C), SerialPeripheral Interface (SPI), PS/2, Universal Serial Bus (USB),Bluetooth®, Infrared Data Association (IrDA), and various radiofrequency (RF) communication protocols defined by the IEEE 802.11 orother standards. In the example of FIG. 1 , the input device 100 maycorrespond to a proximity sensor device (such as a “touchpad” or a“touch sensor device”) configured to sense input provided by one or moreinput objects 140 in a sensing region 120. Example input objects includea finger, palm, capacitive pen, and other such devices. The sensingregion 120 may encompass any space above, around, in and/or near theinput device 100 in which the input device 100 is able to detect a userinput (e.g., provided by one or more input objects 140). The sizes,shapes, and locations of particular sensing regions may vary dependingon actual implementations.

In some embodiments, the sensing region 120 detects inputs involving nophysical contact with any surfaces of the input device 100. In otherembodiments, the sensing region 120 detects inputs involving contactwith an input surface (e.g., a touch screen) of the input device 100coupled with some amount of applied force or pressure.

The input device 100 may utilize any combination of sensor componentsand sensing technologies to detect user input in the sensing region 120.The input device 100 includes one or more sensing elements for detectinguser input. As several non-limiting examples, the input device 100 mayuse capacitive, elastive, resistive, inductive, magnetic, acoustic,ultrasonic, and/or optical techniques. The input device 100 may alsoinclude one or more physical or virtual buttons 130 to collect userinput.

In some embodiments, the input device 100 may utilize capacitive sensingtechnologies to detect user input. For example, the input device 100 mayinclude in the sensing region 120 one or more capacitive sensingelements (e.g., sensor electrodes) that create an electric field. Theinput device 100 may detect inputs from the input object 140 based onchanges in the capacitance of the sensor electrodes. More specifically,an object in contact with (or in close proximity to) the electric fieldmay cause changes in the voltage and/or current in the sensorelectrodes. Such changes in voltage and/or current may be detected as“signals” indicative of user input. The sensor electrodes may bearranged in arrays or other regular or irregular patterns of capacitivesensing elements to create electric fields. These electric fieldscomprise uplink signals that may be detected by an input object 140. Insome implementations, some sensing elements may be ohmically shortedtogether to form larger sensor electrodes. Some capacitive sensingtechnologies may utilize resistive sheets that provide a uniform layerof resistance.

Some capacitive sensing technologies may be based on “self capacitance”(also referred to as “absolute capacitance”) or mutual capacitance (alsoreferred to as “transcapacitance”) or both. Absolute capacitance sensingmethods detect changes in the capacitive coupling between sensorelectrodes and an input object. Transcapacitance sensing methods detectchanges in the capacitive coupling between sensor electrodes. Forexample, an input object near the sensor electrodes may alter theelectric field between the sensor electrodes, thus changing the measuredcapacitive coupling of the sensor electrodes. In some embodiments, theinput device 100 may implement transcapacitance sensing by detecting thecapacitive coupling between one or more transmitter sensor electrodes(also “transmitter electrodes” or “transmitter”) and one or morereceiver sensor electrodes (also “receiver electrodes” or “receiver”).

The processing system 110 may be configured to operate the hardware ofthe input device 100 to detect input in the sensing region 120. Theprocessing system 110 may include parts of, or all of, one or moreintegrated circuits (ICs) and/or other circuitry components. In someembodiments, the processing system 110 also includeselectronically-readable instructions, such as firmware code, softwarecode, and the like. In some embodiments, components composing theprocessing system 110 are located together, such as near sensingelement(s) of the input device 100. In other embodiments, components ofprocessing system 110 are physically separate with one or morecomponents close to the sensing element(s) of the input device 100, andone or more components elsewhere.

For example, the input device 100 may be a peripheral coupled to acomputing device, and the processing system 110 may include softwareconfigured to run on a central processing unit of the computing deviceand one or more ICs (perhaps with associated firmware) separate from thecentral processing unit. As another example, the input device 100 may bephysically integrated in a mobile device, and the processing system 110may include circuits and firmware that are part of a main processor ofthe mobile device. In some embodiments, the processing system 110 isdedicated to implementing the input device 100. In other embodiments,the processing system 110 also performs other functions, such asoperating display screens, driving haptic actuators, and the like. Forexample, the processing system 110 may be part of an integrated touchand display controller.

In some embodiments, the processing system 110 may include sensorcircuitry 160 configured to perform transcapacitance sensing by i)driving one or more transmitter sensor electrodes to transmittransmitter signals and ii) receiving from one or more receiver sensorelectrodes the resulting signals that result from the capacitivecoupling between the transmitter sensor electrodes and the receiversensor electrodes (also “receiver electrodes” or “receiver”).

In some embodiments, the processing system 110 may include determinationcircuitry 150 configured to obtain measurements of the resulting signalsreceived by the receiver sensor electrodes. The determination circuitry150 is configured to determine from the measurements when at least oneinput object is in the sensing region 120, determine signal-to-noiseratio (SNR), determine positional information of an input object,identify a gesture, determine an action to perform based on the gesture,a combination of gestures or other information, or perform otheroperations.

In some embodiments, the processing system 110 operates the sensorelectrode(s) of the input device 100 to produce electrical signalsindicative of input (or lack of input) in the sensing region 120. Theprocessing system 110 may perform any appropriate amount of processingon the electrical signals in producing the information provided to theelectronic system 101. For example, the processing system 110 maydigitize analog electrical signals obtained from the sensor electrodes.As another example, the processing system 110 may perform filtering orother signal conditioning. As yet another example, the processing system110 may subtract or otherwise account for a baseline, such that theinformation reflects a difference between the electrical signals and thebaseline. A baseline is an estimate of the raw measurements of thesensing region when an input object is not present. For example, acapacitive baseline is an estimate of the background capacitance of thesensing region 120. Each sensor electrode may have a correspondingindividual value in the baseline. As yet further examples, theprocessing system 110 may determine positional information, recognizeinputs as commands, recognize handwriting, and the like.

In some embodiments, the input device 100 includes a touch screeninterface, and the sensing region 120 overlaps at least part of anactive area of a display screen 155. The input device 100 may includesubstantially transparent sensor electrodes overlaying the displayscreen 155 and provide a touch screen interface for the associatedelectronic system. The display screen 155 may be any type of dynamicdisplay capable of displaying a visual interface to a user, and mayinclude any type of light emitting diode (LED), organic LED (OLED),cathode ray tube (CRT), liquid crystal display (LCD), plasma,electroluminescence (EL), or other display technology. The input device100 and the display screen 155 may share physical elements. For example,some embodiments may utilize some of the same electrical components fordisplaying and sensing. In various embodiments, one or more displayelectrodes of a display device may be configured for both displayupdating and input sensing. As another example, the display screen 155may be operated in part or in total by the processing system 110.

The sensing region 120 and the display screen 155 may be integrated andfollow on-cell or in-cell or hybrid architectures. In other words,display screen 155 may be composed of multiple layers (e.g., one or morepolarizer layers, color filter layers, color filter glass layers, thinfilm transistor (TFT) circuit layers, liquid crystal material layers,TFT glass layers, etc.). The sensor electrodes may be disposed on one ormore of the layers. For example, the sensor electrodes may be disposedon the TFT glass layer and/or the color filter glass layer. Moreover,the processing system 110 may be part of an integrated touch and displaycontroller that operates both the display functions and the touchsensing functions.

FIG. 2A shows a portion of an example sensor electrode pattern 200 whichmay be utilized in a sensor to generate all or part of the sensingregion of input device 100, according to various embodiments. Inputdevice 100 is configured as a capacitive sensing input device whenutilized with a capacitive sensor electrode pattern. For purposes ofclarity of illustration and description, a non-limiting simplerectangular sensor electrode pattern 200 with a first plurality ofsensor electrodes X and a second plurality of sensor electrodes Y isillustrated. Although the labels X and Y are utilized and FIG. 2Aillustrates that the X and Y sensor electrode subsets are substantiallyorthogonal to one another, an orthogonal relationship between thecrossing first and second subsets of sensor electrodes is not required.

In one embodiment, the sensor electrodes X and Y may be arranged ondifferent sides of the same substrate. For example, each of the firstplurality X and second plurality of sensor electrode may be disposed onone of the surfaces of a substrate. In one such an embodiment, sensorelectrodes X are disposed on a first side of a substrate, while sensorelectrodes Y are disposed on an opposing side of the substrate. In otherembodiments, the sensor electrodes may be arranged on differentsubstrates. For example, each of the each of the first and secondplurality of sensor electrode(s) may be disposed on surfaces of separatesubstrates which may be adhered together.

In another embodiment, the sensor electrodes are all located on the sameside or surface of a common substrate. In one example, a first pluralityof the sensor electrodes comprises jumpers in regions where the firstplurality of sensor electrodes crossover the second plurality of sensorelectrodes, where the jumpers are insulated from the second plurality ofsensor electrodes. In one or more embodiments, the sensor electrodes maycomprise at least one display electrode configured for display updatingand capacitive sensing. The display electrode may be selected from alist comprising, but not limited to, a segment of a segmented Vcomelectrode, a source electrode, a gate electrode, a cathode electrode,and an anode electrode.

The first plurality of sensor electrodes may extend in a firstdirection, and the second plurality of sensor electrodes may extend in asecond direction. The second direction may be similar to or differentfrom the first direction. For example, the second direction may beparallel with, perpendicular to, or diagonal to the first direction.Further, the sensor electrodes may each have the same size or shape ordiffering size and shapes. In one embodiment, the first plurality ofsensor electrodes may be larger (larger surface area) than the secondplurality of sensor electrodes. In other embodiments, the firstplurality and second plurality of sensor electrodes may have a similarsize and/or shape. Thus, the size and/or shape of the one or more of thesensor electrodes may be different than the size and/or shape of anotherone or more of the sensor electrodes. Nonetheless, each of the sensorelectrodes may be formed into any desired shape on their respectivesubstrates.

In other embodiments, one or more of sensor electrodes are disposed onthe same side or surface of the common substrate and are isolated fromeach other in the sensing region 120.

The illustrated sensor electrode pattern in FIG. 2A is composed ofsensor electrodes X (X1, X2, X3, X4) which may be used as bothtransmitter electrodes and receiver electrodes, and sensor electrodes Y(Y1, Y2, Y3, Y5) which may be used as both transmitter electrodes andreceiver electrodes. Sensor electrodes X and Y overlay one another in anorthogonal arrangement, in this example. It is appreciated that in acrossing sensor electrode pattern, such as the illustrated example ofFIG. 2A, some form of insulating material or substrate can be disposedbetween sensor electrodes Y and X. For purposes of clarity, depictionsof these substrates and insulators have been omitted herein.

In the illustrated example of FIG. 2A, capacitive pixels may be measuredvia transcapacitive sensing. For example, capacitive pixels may belocated at regions where transmitter and receiver electrodes interact.The pixels may have a variety of shapes, depending on the nature of theinteraction. In the illustrated example, capacitive pixels are locatedwhere transmitter and receiver electrodes overlap one another.

Capacitive coupling 290 illustrates one of the capacitive couplingsgenerated by sensor electrode pattern 200 during transcapacitive sensingwith sensor electrode Y5 as a transmitter electrode and sensor electrodeX4 as a receiver electrode or with sensor electrode X4 as a transmitterelectrode and sensor electrode Y5 as a receiver electrode.

Capacitive coupling 295 illustrates one of the capacitive couplingsgenerated by sensor electrode pattern 200 during transcapacitive sensingwith sensor electrode Y5 as a transmitter electrode and sensor electrodeY4 as a receiver electrode or with sensor electrode Y4 as a transmitterelectrode and sensor electrode Y5 as a receiver electrode.

Capacitive coupling 297 illustrates one of the capacitive couplingsgenerated by sensor electrode pattern 200 during transcapacitive sensingwith sensor electrode X4 as a transmitter electrode and sensor electrodeY3 as a receiver electrode or with sensor electrode X3 as a transmitterelectrode and sensor electrode X4 as a receiver electrode.

When accomplishing transcapacitive measurements, the capacitivecouplings, are areas of localized capacitive coupling between sensorelectrodes. The capacitive coupling between sensor electrodes changeswith the proximity and motion of input objects in the sensing regionassociated with sensor electrodes. In some instances, areas ofcapacitive coupling such as 290, 295, and 297 may be referred to ascapacitive pixels. It should be noted that the different types ofcapacitive couplings 290, 295, 297 have different shapes, sizes, and ororientations from one another due to the particular nature of theinteractions.

As another example, absolute capacitive couplings may increase where thearea of overlap between a sensor electrode and a user input depending onthe series coupling of the user through a voltage reference (e.g.,system ground) from which the respective receiver is modulated. As oneexample, dashed box 299 represents an area of absolute capacitivecoupling which may be associated with sensor electrode X1; other sensorelectrodes similar have areas of absolute capacitive coupling. As afurther example, the absolute capacitive series couplings may alsoinclude the effect of user coupling to other transmitter electrodes inparallel to the coupling to the reference voltage.

FIG. 2B illustrates an example matrix array of sensor electrodes,according to various embodiments. As illustrated in FIG. 2B, the sensorelectrodes 210 may be disposed in an N×M matrix array where each sensorelectrode may be referred to as a matrix sensor electrode. In oneembodiment, each sensor electrode of sensor electrodes is substantiallysimilar size and/or shape. In one embodiment, one or more of sensorelectrodes of the matrix array of sensor electrodes may vary in at leastone of size and shape. Each sensor electrode of the matrix array maycorrespond to a pixel of a capacitive image. Further, two or more sensorelectrodes of the matrix array may correspond to a pixel of a capacitiveimage.

In various embodiments, each sensor electrode of the matrix array may becoupled a separate capacitive routing trace of a plurality of capacitiverouting traces. In various embodiments, the sensor electrodes 210comprises one or more gird electrodes disposed between at least twosensor electrodes of sensor electrodes. The grid electrode and at leastone sensor electrode may be disposed on a common side of a substrate,different sides of a common substrate and/or on different substrates. Inone or more embodiments, the sensor electrodes and the grid electrode(s)may encompass an entire voltage electrode of a display device. Thevoltage electrode may be selected from a list comprising, but notlimited to, a Vcom electrode, a segment of a segmented Vcom electrode, asource electrode, a gate electrode, a cathode electrode, and an anodeelectrode. Although the sensor electrodes may be electrically isolatedon the substrate, the electrodes may be coupled together outside of thesensing region 120—e.g., in a connection region. In one embodiment, afloating electrode may be disposed between the grid electrode and thesensor electrodes. In one particular embodiment, the floating electrode,the grid electrode and the sensor electrode comprise the entirety of acommon electrode of a display device. Each sensor electrode may beindividually coupled to the processing system or coupled to theprocessing system through one or more multiplexers or switchingmechanisms.

In the illustrated example of FIG. 2B, capacitive pixels may be measuredvia transcapacitive sensing. For example, capacitive pixels may belocated at regions where transmitter and receiver electrodes interact.In the illustrated example, capacitive pixels are located wheretransmitter and receiver electrodes are coupled to one another. Forexample, capacitive coupling 280 illustrates one of the capacitivecouplings generated by sensor electrode pattern 210 duringtranscapacitive sensing with sensor electrode SE1 as a transmitterelectrode and sensor electrode SE2 as a receiver electrode or withsensor electrode SE1 as a transmitter electrode and sensor electrode SE2as a receiver electrode.

Capacitive coupling 281 illustrates one of the capacitive couplingsgenerated by sensor electrode pattern 210 during transcapacitive sensingwith sensor electrode SE1 as a transmitter electrode and sensorelectrode SE3 as a receiver electrode or with sensor electrode SE3 as atransmitter electrode and sensor electrode SE1 as a receiver electrode.

Capacitive coupling 282 illustrates one of the capacitive couplingsgenerated by sensor electrode pattern 210 during transcapacitive sensingwith sensor electrode SE1 as a transmitter electrode and sensorelectrode SE4 as a receiver electrode or with sensor electrode SE4 as atransmitter electrode and sensor electrode SE1 as a receiver electrode.

When accomplishing transcapacitive measurements, the capacitivecouplings, are areas of localized capacitive coupling between sensorelectrodes. The capacitive coupling between sensor electrodes changeswith the proximity and motion of input objects in the sensing regionassociated with sensor electrodes. As one example, dashed box 284represents an area of absolute capacitive coupling which may beassociated with sensor electrode SE4; other sensor electrodes in sensorelectrode pattern 210 similar have areas of absolute capacitivecoupling. The absolute capacitance of any one or more of the sensorelectrodes in sensor electrode pattern 210 may also be measured.

In some embodiments, sensor electrode pattern 200 is “scanned” todetermine these capacitive couplings. That is, sensor circuitry 160drives the transmitter electrodes to transmit transmitter signals.Transmitters may be operated such that one transmitter electrodetransmits at one time, or multiple transmitter electrodes transmit atthe same time. Where multiple transmitter electrodes transmitsimultaneously, these multiple transmitter electrodes may transmit thesame transmitter signal and produce an effectively larger transmitterelectrode, or these multiple transmitter electrodes may transmitdifferent transmitter signals. For example, multiple transmitterelectrodes may transmit different transmitter signals according to oneor more coding schemes that enable their combined effects on theresulting signals of receiver electrodes to be independently determinedbased on the multiple results of multiple independent codes.

In one embodiment, a first sensor electrode may be driven by sensorcircuitry 160 with a first transmitter signal based on a first code of aplurality of distinct digital codes and a second sensor electrode may bedriven with a second transmitter signal based on a second code of theplurality of distinct digital codes, where the first code may beorthogonal to the second code. With regard to FIG. 2B, the sensorelectrodes may be driven and received by sensor circuitry 160 such thatat least two sensor electrodes may be simultaneously driven. In one ormore embodiments, each of the sensor electrodes may be simultaneouslydriven. In such an embodiment, each sensor electrode may be driven witha transmitter signal based on a different one of a plurality oforthogonal digital codes. Further, the sensor electrodes may be drivensuch that a first at least one sensor electrode is driven differentlythat a second at least sensor electrode. In one or more embodiments, thesensor electrodes are driven such that along each row and columnalternating sensor electrodes are driven differently.

The receiver electrodes may be operated singly or in multiples toacquire resulting signals. The resulting signals may be used todetermine measurements of the capacitive couplings at the capacitivepixels. Note that the receiver signals may also be multiplexed such thatmultiple electrodes may be measured with a single receiver (e.g., analogfront end or “AFE”). Furthermore, the receiver multiplexer may beimplemented such that the receiver is simultaneously coupled to andsimultaneously receives resulting signals from multiple sensorelectrodes. In such implementations, the resulting signals comprisecoded results from the multiple sensor electrodes. Note in variousembodiments, that multiple “absolute capacitance” electrodes may bedriven simultaneously with the same modulation relative to a referencevoltage and such that they are guarding each other, or some may bedriven relative to each other modulated relative to a system referencevoltage such that they measure both a transcapacitive and an absolutecapacitive signal simultaneously.

A set of measurements from the capacitive couplings or pixels form a“capacitive image” (also “capacitive frame”) representative of thetranscapacitive couplings. For example, a capacitive image may be madeup of a set of capacitive pixels, such as capacitive coupling 290.Multiple capacitive images may be acquired over multiple time periods,and differences between them used to derive information about input inthe sensing region. For example, successive capacitive images acquiredover successive periods of time can be used to track the motion(s) ofone or more input objects entering, exiting, and within the sensingregion. Also, in various embodiments, a “capacitive image” may be formedby absolute capacitive measurements of a matrix array of sensorelectrodes (e.g., sensor electrode pattern 210 of FIG. 2B). In suchembodiments, sensor electrodes may be operated for absolute capacitivesensing depending on the multiplexer settings. For example, the sensorelectrodes may be grouped into rows, columns and/or other combinationsof sensor electrodes.

A set of measurements from the capacitive coupling/pixels along one axismay be taken to form a “transcapacitive profile” (also “profile frame”)representative of the capacitive couplings at the capacitivecouplings/pixels between parallel electrodes on an axis (e.g.,electrodes X or Y). For example, a transcapacitive profile may be madeup from a set of horizontal capacitive pixels, such as capacitivecoupling/pixel 295, or from a set of vertical pixels, such as capacitivecoupling/pixel 297. Multiple transcapacitive profiles along one or moreaxes may be acquired over multiple time periods, and differences betweenthem used to derive information about input in the sensing region. Forexample, successive transcapacitive profiles acquired over successiveperiods of time for an axis can be used to track the motion(s) of one ormore input objects entering, exiting, and within the sensing region.Alternately, a set of measurements from the capacitive coupling along anaxis may be taken from an “absolute capacitive profile” (also called“ABS profile”) representative of the capacitive couplings between theparallel electrodes on an axis and the series capacitance from the userinput through the coupling to the reference electrode which the absolutereceivers are modulated.

As will be described herein, in some embodiments, combined sensing canbe performed by driving a sensing signal onto a sensor electrode (e.g.,sensor electrode X1) and simultaneously with the driving of that sensorelectrode, other sensor electrodes that cross and do not cross thatsensor electrode (e.g., sensor electrodes Y that cross sensor electrodeX1 and one or more other sensor electrodes X which do not cross sensorelectrode X1) may be used as receivers to obtain transcapacitivemeasurements between themselves and the driven sensor electrode.

FIG. 3 illustrates a method of detecting a capacitive pen according toone or more embodiments of the disclosure. Under normal conditions, thedriving circuitry 160 drives the whole panel with uplink waveformsimultaneously. This method works for the “well grounded” conditionwhere a finger or palm touches the panel or the LGM condition without apalm or finger on the panel. The method disclosed in FIG. 3 is differentthan the normal method and is ideally suited for rapid detection of theinput object 140 in Case 1, wherein a large input object (e.g., palm,finger) reaches the surface of sensing region 120 before the inputobject 140 (i.e., the most common case).

In FIG. 3 , it is assumed that touch sensing is actively running forevery frame. If the sensor circuitry 160 detects the palm of the user insensing region 120 under LGM conditions, then the sensor circuitry 160drives the sensor electrodes in the sensing region 120 according to FIG.3 to generate the uplink signals.

In FIG. 3 , in a first frame (not shown), a large input object (e.g., apalm or finger) is detected at location 310. Further, an LGM state ofthe input device has already been detected for the input device 100. Inresponse to the detection of the large input object at location 310 andthe detection of the LGM state, the sensor circuitry 160 during a secondsubsequent frame uses an inverted signal (represented as “−1”) to drivethe sensor electrodes in the rows and columns of sensor electrodes thatare overlapped by location 310. The sensor circuitry 160 connects all ofthe remaining rows and columns of sensor electrodes to system ground orto another static DC voltage (represented as “0”). The “0” means that nomodulating signal is applied, but the sensor electrodes are not leftfloating.

Thus, the disclosed method in FIG. 3 drives an inverted waveform forrows of sensor electrodes (Group A) and columns of sensor electrodes(Group B) that are covered by region 310 where the palm of the user hasbeen detected. The disclosed method provides no drive signal for theremaining rows and columns of sensor electrodes. As a result of thepattern of drive signals in FIG. 3 , the input device 100 maximizes thedifference between the drive signals at location 310 (where the largeinput object touches the panel) and the rest of the sensing region 120where the input object 140 may touch the panel of the input device 100.

FIG. 4 illustrates a method of detecting a capacitive pen according toone or more embodiments of the disclosure. In FIG. 4 , in a first frame(not shown), a large input object (e.g., a palm or finger) is detectedat location 410. Further, an LGM state of the input device has alreadybeen detected for the input device 100. In response to the detection ofthe large input object at location 410 and the detection of the LGMstate, the sensor circuitry 160 second subsequent frame connects thesensor electrodes in the rows and columns that are overlapped bylocation 410 to system ground or to another static DC voltage(represented as “0”). The sensor circuitry 160 in the second subsequentframe uses a non-inverted signal (represented as “1”) to drive thesensor electrodes in all of the remaining rows and columns of sensorelectrodes.

Thus, the disclosed method in FIG. 4 uses a system ground or anotherstatic DC voltage to drive the rows of sensor electrodes (Group B) andcolumns of sensor electrodes (Group B) that are covered by region 410where the palm of the user has been detected. The disclosed method usesa non-inverted signal for the remaining rows and columns of sensorelectrodes outside of Group A and Group B. As a result of the pattern ofdrive signals in FIG. 4 , the input device 100 maximizes the differencebetween the drive signals at location 410 (where the large input objecttouches the panel) and the rest of the sensing region 120 where theinput object 140 may touch the panel of the input device 100.

FIG. 5 illustrates normalized uplink signal levels during capacitive pendetection in FIG. 3 according to one or more embodiments. In FIG. 5 ,the uplink signal values in FIG. 3 are normalized using the location 510where the large input object is detected as a zero reference. Thus,location 510, where a user's palm touches the panel, has an uplinksignal level of “0”. The four (4) regions 511-514 that are not coupledto location 510 (i.e., rows and columns of sensor electrodes that do notintersect location 510) have a signal level of “2”. The remaining four(4) regions have either rows of sensor electrodes or columns of sensorelectrodes, but not both, that intersect with location 410, therebyproducing uplink signal levels of “1”.

The uplink transmission patterns of FIGS. 3 and 4 minimize the uplinksignal amplitude near location 510 in FIG. 5 and maximizes the value atall other areas (ranges from +1 to +2). The differences in the uplinksignals determines the signal level seen by the input object 140attempting to receive the uplink signals. As a result, the input object140 may be detected for all the regions not covered by palm within one(1) frame, thereby reducing latency by, for example, 16.7 milliseconds.

FIG. 6 is a flow diagram illustrating uplink driving according to one ormore embodiments. In block 610, touch sensing happens regularly at acertain frame rate (e.g., once per frame). At some point, the sensorcircuitry 160 in block 620 determines if a low ground mass condition anda large input object (e.g., user palm) have both been detected. If No inblock 620, then the driving circuitry 160 in block 630 drives the sensorelectrodes in the entire panel with non-inverted signals using thenormal method when the LGM condition is not detected or if no finger orpalm or other object is touching the display panel.

If Yes in block 620, then the sensor circuitry 160 in block 640 drivesthe sensor electrodes in the sensing region using the method describedin FIG. 3 or the method described in FIG. 4 . After either block 630 orblock 640, the input device 100 in block 650 continues to perform othersteps of input object 140 detection, such as tracking the location ofthe input object 140 if the input object 140 transmits anacknowledgement signal.

While the invention has been described with respect to a limited numberof embodiments, those skilled in the art, having benefit of thisdisclosure, will appreciate that other embodiments can be devised whichdo not depart from the scope of the invention as disclosed herein.Accordingly, the scope of the invention should be limited only by theattached claims.

What is claimed is:
 1. A processing system configured to detect an inputobject proximate the processing system comprising: sensor circuitryconfigured to: determine that the processing system is in a low groundmass (LGM) state, determine an object having a size exceeding the inputobject is proximate to a plurality of sensor electrodes, the pluralityof sensor electrodes arranged in substantially orthogonal rows andcolumns and configured to transmit uplink signals to the input object;and in response to the object being determined proximate to theplurality of sensor electrodes and the processing system in the LGMstate, drive a first group of the plurality of sensor electrodes withone of an inverted modulated signal or a non-inverted modulated signal,and drive a second group of the plurality of sensor electrodes with astatic non-modulated DC voltage, wherein the first group of theplurality of sensor electrodes comprises at least one row of sensorelectrodes that intersect a location where the object is proximate theplurality of sensor electrodes.
 2. The processing system of claim 1,wherein the static non-modulated DC voltage is a system ground voltage.3. The processing system of claim 1, wherein the input object is acapacitive pen.
 4. The processing system of claim 1, wherein, when theprocessing system is not in LGM state, the sensor circuitry drives eachof the plurality of sensor electrodes with the non-inverted modulatedsignal.
 5. The processing system of claim 1, wherein the first group ofthe plurality of sensor electrodes comprises at least one column ofsensor electrodes that intersect the location where the object isproximate the plurality of sensor electrodes.
 6. The processing systemof claim 5, wherein the second group of the plurality of sensorelectrodes comprises at least one row of sensor electrodes that do notintersect the location where the object is proximate the plurality ofsensor electrodes.
 7. The processing system of claim 6, wherein thesecond group of the plurality of sensor electrodes comprises at leastone column of sensor electrodes that do not intersect the location wherethe object is proximate the plurality of sensor electrodes.
 8. A methodof detecting an input object proximate a processing system comprising:determine that the processing system is in a low ground mass (LGM)state, determine an object having a size exceeding the input object isproximate to a plurality of sensor electrodes, the plurality of sensorelectrodes arranged in substantially orthogonal rows and columns andconfigured to transmit uplink signals to the input object; and inresponse to the object being determined proximate to the plurality ofsensor electrodes and the processing system in the LGM state, drive afirst group of the plurality of sensor electrodes with one of aninverted modulated signal or a non-inverted modulated signal, and drivea second group of the plurality of sensor electrodes with a staticnon-modulated DC voltage, wherein the first group of the plurality ofsensor electrodes comprises at least one row of sensor electrodes thatintersect a location where the object is proximate the plurality ofsensor electrodes.
 9. The method of claim 8, wherein the staticnon-modulated DC voltage is a system ground voltage.
 10. The method ofclaim 8, wherein the input object is a capacitive pen.
 11. The method ofclaim 8, wherein, when the processing system is not in LGM state, themethod further includes driving each of the plurality of sensorelectrodes with the non-inverted modulated signal.
 12. The method ofclaim 8, wherein the first group of the plurality of sensor electrodescomprises at least one column of sensor electrodes that intersect thelocation where the object is proximate the plurality of sensorelectrodes.
 13. The method of claim 12, wherein the second group of theplurality of sensor electrodes comprises at least one row of sensorelectrodes that do not intersect the location where the object isproximate the plurality of sensor electrodes.
 14. The method of claim13, wherein the second group of the plurality of sensor electrodescomprises at least one column of sensor electrodes that do not intersectthe location where the object is proximate the plurality of sensorelectrodes.
 15. An input device configured to detect an input objectproximate the input device comprising: a plurality of sensor electrodesarranged in substantially orthogonal rows and columns and configured totransmit uplink signals to the input object; and a processing systemcoupled to the plurality of sensor electrodes, the processing systemconfigured to: determine that the processing system is in a low groundmass (LGM) state, determine an object having a size exceeding the inputobject is proximate to the plurality of sensor electrodes; and inresponse to the object being determined proximate to the plurality ofsensor electrodes and the processing system in the LGM state, drive afirst group of the plurality of sensor electrodes with one of aninverted modulated signal or a non-inverted modulated signal, and drivea second group of the plurality of sensor electrodes with a staticnon-modulated DC voltage, wherein the first group of the plurality ofsensor electrodes comprises at least one row of sensor electrodes thatintersect a location where the object is proximate the plurality ofsensor electrodes.
 16. The input device of claim 15, wherein the staticnon-modulated DC voltage is a system ground voltage.
 17. The inputdevice of claim 15, wherein the input object is a capacitive pen. 18.The input device of claim 15, wherein, when the processing system is notin LGM state, the processing system drives each of the plurality ofsensor electrodes with the non-inverted modulated signal.
 19. The inputdevice of claim 15, wherein the first group of the plurality of sensorelectrodes comprises at least one column of sensor electrodes thatintersect the location where the object is proximate the plurality ofsensor electrodes.
 20. The input device of claim 19, wherein the secondgroup of the plurality of sensor electrodes comprises: at least one rowof sensor electrodes that do not intersect the location where the objectis proximate the plurality of sensor electrodes; and at least one columnof sensor electrodes that do not intersect the location where the objectis proximate the plurality of sensor electrodes.